<template>
  <div id="map">
    <div class="setting">
      <div class="slider">
        <span>热点半径（radius size）：</span>
        <el-slider v-model="state.radiusSize" @input="handleRadiusChange" />
      </div>
      <div class="slider">
        <span>模糊尺寸（blur size）：</span>
        <el-slider v-model="state.blurSize" @input="handleBlurChange" />
      </div>
    </div>
  </div>
</template>

<script  setup>

import { onMounted, reactive, onBeforeUnmount } from "vue";
import { Map, View } from "ol";
import { Tile as TileLayer, Heatmap } from "ol/layer";
import { defaults, FullScreen } from "ol/control";
import { XYZ, Vector as VectorSource } from "ol/source";
import { KML } from "ol/format";
import { MAPURL, ATTRIBUTIONS } from "../../constants";

let map;
const state = reactive({
  radiusSize: 10,
  blurSize: 15,
});
//创建一个Heatmap图层
const vector = new Heatmap({
  //矢量数据源（读取本地的KML数据）
  source: new VectorSource({
    url: "/kml/Earthquakes_Mag5.kml",
    format: new KML({
      extractStyles: false,
    }),
    wrapX: false,
  }),
  //热点半径
  radius: state.radiusSize,
  //模糊尺寸
  blur: state.blurSize,
});
//为矢量数据源添加addfeature事件监听
vector.getSource()?.on("addfeature", event => {
  // 示例数据2012_Earthquakes_Mag5.kml，可从其地标名称提取地震信息
  //要素的名称属性
  const name = event.feature?.get("name");
  //得到要素的地震震级属性（magnitude）
  const magnitude = parseFloat(name.substr(2));
  //设置要素的weight属性
  event.feature?.set("weight", magnitude - 5);
});
const raster = new TileLayer({
  source: new XYZ({
    attributions: ATTRIBUTIONS,
    url: MAPURL,
    maxZoom: 20,
  }),
});
const initMap = () => {
  map = new Map({
    //初始化map
    target: "map",
    //地图容器中加载的图层
    layers: [
      //加载瓦片图层数据
      raster,
      vector,
    ],
    view: new View({
      projection: "EPSG:4326", // 坐标系，有EPSG:4326和EPSG:3 857
      center: [0, 0],
      //地图初始显示级别
      minZoom: 2,
      zoom: 2,
    }),
    //加载控件到地图容器中
    controls: defaults().extend([
      new FullScreen(), //加载全屏显示控件（目前支持非IE内核浏览器）
    ]),
  });
};
// 设置热点半径
const handleRadiusChange = () => {
  //设置热点图层的热点半径
  vector.setRadius(state.radiusSize);
};
// 设置模糊尺寸
const handleBlurChange = () => {
  //设置热点图层的模糊尺寸
  vector.setBlur(state.blurSize);
};
onMounted(() => {
  initMap();
});
onBeforeUnmount(() => {
  if (map) {
    map.dispose();
    map = null;
  }
});
</script>

<!-- Add "scoped" attribute to limit CSS to this component only -->
<style scoped>
#map {
  position: relative;
  height: 100%;
}
.setting {
  position: absolute;
  top: 50px;
  right: 20px;
  width: 400px;
  height: 200px;
  z-index: 1;
  color: #fff;
  font-weight: bold;
}
</style>